presents the N’s and characteristics of each of the subthreshold groups at T1. Women were more likely to have subthreshold MDD and anxiety and men were more likely to have subthreshold conduct disorder and ADHD. Participants in all subthreshold groups were more likely than their respective control groups to have co-occurring subthreshold and FS conditions. Those with subthreshold MDD, alcohol, substance, conduct and ADHD were slightly older at T1 than their respective control groups as well. Because of the small differences in ages, we did not adjust for baseline age in the Cox models below.
Characteristics of subthreshold groups at T1.
Predicting FS conditions at follow-up (T2 thru T4)
We first determined what percentage of the sample developed a disorder for the first time during the follow-up period (i.e., excluding those with each respective baseline diagnosis). First time incidence rates were 24.5% (N=294) for depression, 1.2% (N=18) for bipolar disorder, 9.8% (N=136) for anxiety disorders, 21.2% (N=304) for alcohol, 12.1% (N=171) for substance use disorder, and 1.6% (N=24) for conduct disorder/ASPD (ASPD). presents the results of which diagnostic groups at T1 developed which FS conditions at follow-up adjusted for gender. As noted above, no subjects developed FS ADHD during the follow-up, hence this was not included as an outcome.
Predicting first onset of FS conditions during T2–T4 from baseline FS and SUB conditions (not adjusted for comorbidity)
In , the middle row of each condition presents the results for the subthreshold conditions. With the exception of subthreshold bipolar disorder, homotypic escalations were observed as subthreshold conditions significantly predicted a first onset of the FS condition over time. We also observed the following heterotypic developments. Those with subthreshold bipolar disorder developed FS depressive and anxiety disorders. Those with subthreshold alcohol developed FS substance use disorder and conduct disorder/ASPD. Those with subthreshold substance developed FS alcohol use disorders and a trend for bipolar and anxiety disorders. Those with subthreshold conduct developed FS bipolar, anxiety, alcohol use, and substance use disorders. Those with subthreshold ADHD developed FS alcohol and substance use disorders, and conduct disorder/ASPD.
We next examined whether the heterotypic results for FS conditions were similar to that of the subthreshold conditions. These results are presented in the top row of each condition in . The majority of the heterotypic associations observed for subthreshold conditions were also found for FS conditions. However, FS disorders were associated with more conditions at follow-up than subthreshold conditions.
Predicting follow-up FS disorders adjusting for comorbidity
The second set of analyses examined whether the significant homotypic and heterotypic associations reported in the previous section were due to comorbid conditions. Because the focus of this study is on subthreshold psychopathology, these analyses were only conducted for subthreshold conditions. A covariate was included if it was significantly associated with the IV (i.e., subthreshold condition at T1) and the DV (i.e., follow-up FS diagnoses) in . As an example of how comorbidity was adjusted, subthreshold anxiety, subthreshold conduct, and FS MDD were included as covariates in the model examining whether subthreshold bipolar predicted onset of anxiety. Thus, each analysis, by necessity, included a different set of covariates. presents the T1 associations among subthreshold and FS conditions.
Associations among proband subthreshold (SUB) and full syndrome (FS) conditions at T1 (Total N=1505)
The results of the models adjusting for comorbid subthreshold and FS conditions are displayed in . Only the cells that were significant in the analyses are included in . With the exception of subthreshold anxiety, all of the homotypic escalations from remained significant after adjusting for comorbidity. The majority of the heterotypic developments also remained significant after adjusting for comorbidity with three exceptions: subthreshold conduct disorder no longer predicted FS anxiety disorder, subthreshold ADHD no longer predicted FS alcohol use disorder, and subthreshold alcohol no longer predicting FS substance use disorder.
Subthreshold conditions predicting first occurrence of full syndrome disorders adjusting for comorbidity